The coronavirus or SARS-CoV-2, the virus responsible for the Covid-19 worldwide pandemic. The virus is highly contagious, even though the mortality rate of the virus is low when compared to other deadly diseases, it is still a danger to us. There are two types of test kits that can detect coronavirus in our system, they are antigen and antibody rapid test kits. Do you know how those two test kits work? What are the differences between the two? There has been quite a debate about which test kit is better than the other, which is more reliable. There have been far too many information going around regarding these test kits and this makes it difficult for the general public to find out more. Let's put aside the coronavirus factor, just for a moment let's forget about the fact that we're going through a pandemic, somewhat a life and death situation. Allow me to enlighten you on this matter.
1. Antibody Rapid Test Kit
Let's start with the antibody rapid test kit. I'll set the scene for you.
Imagine, a high level security facility that is safeguarding a national asset, heavily guarded by the best of the best security personnel. A group of highly specialized thieves attempt to break into the facility. They managed to bypass the security system, getting closer and closer towards their goal, however, a mistake was made and they triggered the alarm system, alerting the security personnel on site. The thieves have no escape route, they are left with no other choice but to surrender.
Based on the story;
High level security facility = the human body Security personnel = antibodies,
Alarm system = body's immune system Thieves = antigen
Our body produces antibodies, proteins that are produced to fight off invaders in our body, the invaders are called antigens, any form of substance that triggers the immune system of our body. The story above is a visualization of a normal body function and it happens 24/7 without a break. The human body works very hard because at any moment we could be infected. The antibody rapid test kits detects the presence of antibodies and it can be detected for months to years after the infection. It is a quantitative test which means it is able to determine the amount of antibodies present in the body.
This test is normally done by taking a blood sample. It gives a more accurate representation of an infection's overall impact, and it can aid in tracking the virus's spread and death rate. Another interesting fact is that those who were tested positive for the antibodies and have been recovered from the infection can donate their plasma to to patients that are currently infected. However, there is downside to this testing because no human creation has ever been 100% perfect. If a person were to be tested negative, it does not mean they are not infected, it could mean the person has an active infection but their body has not build up any antibodies. Furthermore, the degree of immunity developed and how long it lasts remains unknown.
2. Antigen Rapid Test Kit
Have you ever played jigsaw puzzles? Jigsaw puzzle pieces have irregular designs, the pieces are designed in a way that each puzzle piece is connected to other pieces perfectly. The human body is a complex organism, for every antigen that invades our body there is an antibody that matches it, just like when two pieces of jigsaw puzzle fit together perfectly. The part of antigen that matches with the antibody is referred to as the specific binding site. To determine the presence of antigen in the system, the test kit detects the specific binding site of the antigen.
An antigen rapid test is a qualitative test, it can only tell us whether the antigen is absent or present. It is relatively cheap and is suitable for point-of care patients which means the test can be done on the spot and it produces a result in an instant. However, its accuracy is a setback because it is not as sensitive as the polymerase chain reaction testing or PCR. Testing with PCR produces a more accurate result because the process amplifies the viral RNA making it easier to detect the presence of the virus. The test is able to determine if the person has an active infection and it can only be used when the antigen is present. Once the person is recovered, the antigen will disappear.
The table below shows a simple comparison between the two types of test kits.
The table below shows some of the examples of rapid test kits from a company called Atlas Medical. It is a biomedical company specializes in manufacturing and supply diagnostic reagents and kits. Besides selling rapid test kit to detect antibody and antigen, rapid test kits to detect other markers are available as well, such as for fertility, cancer markers, cardiac markers, and much more
For more information regarding these test kits, you can visit the link below. This webpage provides information on other rapid test kits and not just antigen and antibody rapid test kits.
In my opinion, there is no such thing as which test kit is better than the other. They were both designed for different purposes. There is a general misconception that the antibody test kit is the better choice because it makes people believe that they are immune to the infection now that they have recovered from it, however, the reality is far from it. With the novel coronavirus, scientists still have not been able to determine if a person is immune once recovered and testing positive for the antibodies means that at some point you were infected and without realizing you have spread the virus to other people. The safest thing to do is to take precautionary steps and if you are showing symptoms, immediately go to a testing centre.
Reference
MacDonald, A. (2020, September 08). Antibody vs Antigen Testing for COVID-19. Retrieved November 07, 2020, from https://www.technologynetworks.com/diagnostics/articles/antibody-vs-antigen-testing-for-covid-19-336486